The present invention relates to a linear transfer device suitable for transferring wafery works, for example, silicon wafers.
In transferring wafery works such as silicon wafers from a supplying station to the following working stations to treat them, they have been transferred in lying positions because this position is the most stable.
In case of such transfer in a lying position, however, dusts tend to stick to the surfaces, and only a slight eccentric load applied on the wafers produces bending or internal stress exerting bad influences on the subsequent working processes, thereby lowering the yield.
To the contrary, if they are linearly transferred in erect positions, a chucking mechanism for securely holding them and its driving mechanism must be provided to make them stable, and such results in complexity of the construction of the device and high cost. In addition, such a chucking mechanism is not suitable for the works that must be delicately treated, such as silicon wafers, because it it too rigid for them. However, the linear transfer in an erect position is advantageous in respect that the adhesion of dusts and the production of bending or internal stress can be reduced.
The present invention was made in view of the abovementioned background and its objects is to provide a linear transfer device for wafery works which can transfer them to different stations while holding them in erect positions and which can receive or deliver them in each station.
To achieve the objects of this invention, the device is characterized in that the reception or delivery of the works can be made only by the vertical movement of a transfer bar relatively to each work supporting means and that the supporting means can be positioned at the retreated positions to prevent interference with the transfer bar when it is in movement.